The present invention relates to an information recording and reproducing device for use with an optical disc.
As is well known, various types of information recording and reproducing devices have been proposed for recording information onto and reading recorded information out of an optical disc by means of a laser beam emitted from a semiconductor laser means.
These information recording and reproducing devices can be grouped into two types: one type does not change the recording current of the semiconductor laser means, while the other type increases the peak light amount of recording signal as its laser comes closer to the outer circumference of the optical disc, the laser recording information on the optical disc, in the radial direction thereof, commencing at the inner circumference.
The first-mentioned type wherein the recording current is left unchanged at the inner and outer circumferential portions of the optical disc has the disadvantages that information cannot be sufficiently recorded on the optical disc at the outer circumferential portion thereof and that recording becomes more and more difficult because the output of the semiconductor laser means changes with time.
The second-mentioned type wherein the peak light amount of recording signal is increased more and more as its laser comes nearer the outer circumference of the optical disc has also the disadvantage that the load imposed on the semiconductor laser means is too much results in excessive use of the laser means.